Twelve 160-lbf thrust MR-104G engines, arranged in four single-engine pods and four dual-engine pods, provide the full complement of primary and redundant control required for critical maneuvers upon a high-speed re-entry into Earth's atmosphere.

The first phase of the MR-104G design verification testing was a critical milestone in the development of the Orion Crew Module propulsion system and marks a significant step toward Orion's first orbital flight test. Orion-specific environment, performance and life requirements were demonstrated as part of this test program in support of the flight test plan. The design verification testing program consisted of vibration and shock testing to appropriately stress the engine structure and catalyst bed similar to launch environments prior to engine hot fire testing. The hot fire test then demonstrated the engine performance and life capability, along with thermal model validations with cold starts, hot restarts and deep thermal cycles.

Several new design features for the MR-104G engine were demonstrated in this testing series, including a newly developed 120-volt series-redundant propellant valve, a 120-volt/40 watt catalyst bed heater, a new chamber pressure transducer and an integral thruster mount configuration.

The MR-104 engine family originally provided in-space propulsion for the Voyager 1 and 2 and Magellan missions. Subsequent MR-104 variants provided propulsion for Landsat, NOAA as well as other U.S. government programs.

"Aerojet is very proud of its support of the crew module's liquid propulsion systems for the Orion spacecraft," said Sam Wiley, Aerojet's Orion program director. "We are excited to provide spacecraft propulsion engines to be used for the next generation of human spaceflight and continue our track record of 100 percent mission success for NASA's human spaceflight dating back to Apollo."